Radio frequency (RF) devices, such as cell phone receivers, are becoming increasingly complex due to requirements to operate according to different modes of operation associated with, for example, additional frequency bands, more complex modulation schemes, higher modulation bandwidths, and the introduction of data throughput improvement schemes such as simultaneous RF transmission and/or reception within a same or different, but closely spaced, bands or channels within a band (e.g. voice, data), and aggregate reception wherein information is multiplexed over parallel RF transmissions.
In order to support such different modes of operation, use of mode specific amplifiers may be one option, where performance of the amplifier may be tuned according to the specific mode. One well known amplifier configuration is a cascode configuration where a plurality of series connected transistors (stacked transistors) are used to amplify an input RF signal. The above referenced papers, whose disclosures are incorporated herein by reference in their entirety, provide more details on design, manufacturing, operation, biasing, tuning and optimization of such cascode configuration.
As the number of modes increases, use of mode specific amplifiers may become too costly and unpractical. For example, considering the high number of different frequency bands that an RF device, such as a cell phone transmitter and/or receiver, may need to support, the traditional approach of adding band specific narrow band amplifiers for each of the supported frequency bands may be prohibitive due to its high cost and required large physical size.
It is therefore an object of the present disclosure to provide a solution to the traditional approach of using mode specific amplifiers while reducing a performance degradation associated with the provided solution.